1. Field of the Invention
This invention relates to a level wound coil (hereinafter called as “LWC”), a method of manufacturing the LWC and a package for the LWC, and more particularly, to an LWC that is formed winding a metal pipe, such as a copper and copper alloy pipe, which is used as a heat transfer pipe of an air-conditioning heat exchanger, a water pipe etc. Furthermore, this invention relates to a method of manufacturing the LWC and a package for the LWC.
2. Description of the Related Art
A heat transfer pipe such as an inner grooved tube/pipe and a smooth (plain) tube/pipe is used for the air-conditioning heat exchanger, the water pipe etc. The heat transfer pipe is typically formed of a copper or copper alloy pipe (hereinafter simply called as “copper pipe”). In the manufacturing process thereof, the pipe is coiled and then annealed into a given tempered material. Then, it is stored or transported in the form of the LWC. In use, the LWC is uncoiled and cut into a pipe with a desired length.
When the LWC is used, the copper pipe is fed out from the LWC by using a copper pipe feeding apparatus (uncoiler). For example, JP-A-2002-370869 discloses a copper pipe feeding apparatus, which will be explained below.
FIGS. 13A and 13B are diagrams showing conventional copper pipe feeding apparatuses. FIG. 13A is a perspective view showing a conventional copper pipe feeding apparatus (vertical uncoiler). FIG. 13B is a perspective view showing a conventional copper pipe feeding apparatus (horizontal uncoiler).
As shown in FIG. 13A, the copper pipe feeding apparatus 10A is operated such that a bobbin 21 with an LWC 20 coiled around there is vertically attached, and a copper pipe 22 is fed from the bobbin 21 while being guided by a guide 11 in a feeding direction. Then, it is cut into a pipe with a desired length by a cutter (not shown).
As shown in FIG. 13B, the copper pipe feeding apparatus 10B is operated such that the bobbin 21 with the LWC 20 coiled around there is horizontally disposed on a turntable 12, and the copper pipe 22 is fed from the bobbin 21 while being guided by a guide 13 in a feeding direction. Then, it is cut into a pipe with a desired length by a cutter (not shown).
FIG. 14 is a cross sectional view showing a detailed arrangement of LWC coiled around the bobbin in FIG. 13A or 13B. As shown in FIG. 14, the LWC 20 is structured with the copper pipe coiled around the bobbin 21. The bobbin 21 comprises an inner cylinder 23 around which the copper pipe 22 is coiled in multiple layers, and a pair of disk-like side boards 24 attached to both sides of the inner cylinder 23.
However, the copper pipe feeding apparatuses 10A, 10B as shown in FIGS. 13A and 13B have a problem that the structure is complicated and the cost thereof increases.
In order to solve this problem, JP-A-2002-370869 discloses a copper pipe feeding method called “Eye to the sky” (hereinafter called ETTS). The method “Eye to the sky” is also called as “Inner end payoff (ID payoff)”.
FIG. 15 is a perspective view showing the method of feeding a copper pipe by the ETTS method. An LWC assembly 30 has plural LWC's 32 that are stacked through a cushioning material 33 such that its center axis is directed perpendicularly to the upper surface of a pallet 31. The pallet 31 is usually formed rectangular and comprises plural wooden square logs 31a and one or more wooden board 31b attached on the square logs 31a. The cushioning material 33 is formed of wood, paper or plastics and has a disk shape with a larger diameter than that of the LWC 32. The cushioning material 33 is often inserted between the pallet 31 and the LWC 32.
As shown in FIG. 15, the LWC 32 has an outside diameter of about 1000 mm and an inside diameter of 500 to 600 mm. The total height of the LWC assembly 30 including the pallet 31 is about 1 to 2 m.
The method of feeding a copper pipe by the ETTS method will be explained below referring to FIG. 15.
The copper pipe 35 is fed upward from the inside of the top LWC 32 in the LWC assembly 30. Then, in order to cut the copper pipe 35 on a pass line set horizontally about 1 m over the floor, the feeding direction is changed by a guide 34 disposed above the LWC assembly 30. Then, the copper pipe 35 is cut into a desired length by a cutter. A circular arc as the guide 34 is formed from a metal or plastic tube and has an inner diameter larger than an outer diameter of the copper pipe 35. The height from the plane on which to place the pallet 31 to the guide 34 is about 2.5 to 3.5 m. The cutter cuts the copper pipe on the pass line set horizontally about 1 m over the floor in a horizontal state. The ETTS method is a method in that the pipe is fed upward from the inside of the LWC disposed such that a coil center axis is perpendicular to a mounting surface of the pallet 31.
The ETTS method is advantageous in removing the purchase cost of the bobbin since the bobbin 21 shown in FIG. 14 is not needed. Further, as shown in FIG. 15, since it is not needed to rotate the LWC, the uncoiler and turntable as shown in FIGS. 13A and 13B are not needed, either. Thus, the facility cost can be significantly reduced.
A method of coiling the LWC 32 will be explained below referring to FIG. 14.
As shown in FIG. 14, for example, the copper pipe 22 is wound on the inner cylinder 23 of the bobbin 21 from a copper pipe 22a at start position to the right direction in alignment winding. The alignment winding is a method that the copper pipe 22 is wound in a circuit around the inner cylinder 23 and then it is wound in the next circuit in close contact with the previous circuit not to have a gap therebetween.
As shown in FIG. 14, after the copper pipe 22 is wound up to the right end to have a cylinder form as the first layer, the second layer is wound on the first layer in alignment winding along the center-axis direction of the LWC from the right end to the left end (in the reverse direction). At that time the copper pipe of the second layer is wound to be engaged in a concave portion formed between adjacent copper pipes in the first layer, namely, the copper pipe of the second layer is arrayed in close-packed alignment to that of the first layer. Further, the third layer coil is formed on the second layer coil in the same way. This is called traverse winding, where after the first-layer cylindrical coil is formed, the second-layer cylindrical coil is wound in the reverse direction along the center-axis direction of the LWC. By winding the copper pipe 22 as described above, the LWC can be reduced in volume and, therefore, a space needed in storing and transporting can be reduced.
FIG. 16 is a schematic cross sectional view illustrating an uncoiling method in LWC. FIG. 16 indicates the uncoiling state when the LWC 20 is uncoiled by the ETTS method, where the LWC 20 is produced such that the copper pipe 22 is wound around the bobbin 21 by the coiling method as shown in FIG. 14, removing the bobbin 21, disposing the LWC 20 on the cushioning material 33 as shown in FIG. 15. At first, the copper pipe 22a at start position on the inner layer side is fed upward. After the feeding of the first-layer is completed, the feeding of the second layer begins from a copper pipe 22b at lower end. Subsequently, the third layer adjoined outside of the second layer is fed from the upper end to the lower end.
However, the uncoiling method in LWC as shown in FIG. 16 has the next problems. When the LWC 20 is set as the LWC 32 in FIG. 15, for example, the copper pipe 22b at lower end of the second layer is sandwiched between the cushioning material 33 (or the pallet 31) and a copper pipe 22 lying directly thereon. Therefore, it may be difficult to feed the copper pipe 22b due to the friction. When the friction in feeding is increased, the copper pipe 22 may be subjected to a bend or kink, resulting in product failure. Further, copper pipes 22b at the lower end of even-numbered layers, i.e., the second and fourth layers etc can have the same problem.
In this regard, JP-A-2002-370869 (FIGS. 3 and 7) discloses an uncoiling method to facilitate the feeding of a copper pipe 22b at lower end in the ETTS method.
FIGS. 17 and 18 (corresponding to FIGS. 3 and 7, respectively, of JP-A-2002-370869) are schematic cross sectional views illustrating the uncoiling method to facilitate the feeding of a copper pipe at lower end.
One-side section of LWC 40 as shown in FIG. 17 is structured such that a copper pipe 41a at start position is located on the top, where an odd-numbered layer has n pipes (circuits) and an even-numbered layer has (n−1) pipes (circuits). The n is a natural number of 2 or more, typically 10 or more, and the pipes are wound in alignment winding.
In LWC 40 as shown in FIG. 17, the LWC 40 is fed upward from the inside of the LWC, for example, the copper pipe 41a at start position on the inner layer side is fed upward, and the copper pipe at lower level is successively fed for every one circuit. After the feeding of a lowermost level of the first-layer is completed, the feeding of the second layer begins from a copper pipe 41b at lower end. In this case, since a gap exists between the copper pipe 41b at lower end of the second layer and the cushioning material 33 or pallet 31, the copper pipe 41b is less likely to be subjected to the resistance of the friction. Thus, the copper pipe 41 can be fed stably.
In contrast, FIG. 18 shows one-side section of LWC 40 that a copper pipe 41a at start position (at a starting section for winding) is located at the bottom close to the cushioning material 33. The copper pipe 41a at start position on the inner layer side is fed upward from the lower end to the upper end. As shown in FIG. 18, an odd-numbered layer has n pipes (circuits) and an even-numbered layer also has n pipes (circuits). After the feeding of the first-layer is completed, the feeding of the second layer begins from a copper pipe 41 at the upper end. In this case, since a copper pipe 41 at lower end of the second layer is not sandwiched when the copper pipe 41 turns upward, the copper pipe 41 can be fed stably as well as the case in FIG. 17.
Meanwhile, the above is taught in paragraphs [0009] to [0012] [0014] to [0017], [0039], [0042], [0062], and [0063] and FIGS. 3, 7 and 14 of JP-A-2002-370869.
However, the conventional uncoiling method of JP-A-2002-370869 has the next problem. In the LWC wound as shown in FIG. 17, a connection from the copper pipe 41 at lower end of the first layer to the copper pipe 41b at lower end of the second layer is exactly formed of a continuous copper pipe, though seen as separate pipes in the cross sectional view of FIG. 17. Thus, the copper pipe 41 is continuously shifted outward and upward in a shift (transition) section on the circuit. The shift section exists in a predetermined part on the circumference at an outer layer side in a radius direction of the coil and upward in the coil center axis direction. When the length of a transition part moving to an outer layer side in a coil radius direction of the shift section increases, namely, a start of moving upward to a perpendicular direction is late, the gap under the copper pipe 41 may substantially disappear. Namely, the copper pipe 41b at lower end may be sandwiched between the cushioning material 33 or the pallet 31 and the copper pipe 41 lying directly thereon. Therefore, it may be difficult to feed the copper pipe 41 and the copper pipe 41 may be subjected to a bend (kink and/or plastic buckling).
The shift section that the copper pipe is shifted to the next-layer (i.e., the outer layer) will be explained later.